Applicant claims priority under 35 U.S.C. xc2xa7119 of German Application No. 199 31 195.1, filed Jul. 7, 1999. Applicant also claims priority under 35 U.S.C. xc2xa7120 of PCT/DE00/01324, filed Apr. 27, 2000. The international application under PCT article 21(2) was not published in English.
1.Field of the Invention
The invention relates to a pneumatic spring system comprising at least the following components, specifically
a pneumatic spring cover and a pneumatic spring piston, which are arranged opposing each other;
a pneumatic spring bellows made of elastomer material, which connects the pneumatic spring cover and the pneumatic spring piston with each other with the use of fastening means, said pneumatic spring bellows being provided with an embedded reinforcement in most cases, whereby the bellows is capable of rolling off on the outer wall of the piston with formation of an interior chamber of the pneumatic spring having an elastic volume; as well as
a connection for ventilating and evacuating the interior chamber of the pneumatic spring.
2.The Prior Art
A pneumatic spring system of said type is described, for example in the published patent documents DE 42 28 513 A1 and WO 98/54016 A1.
Pneumatic spring systems may be in the following two conditions:
(a) Filled with air (operating condition), or
(b) evacuated.
Now, the following problem is posed in conjunction with pneumatic spring systems of vehicles, in particular with vehicles that are lifted by a crane. When the vehicle is set down again, the bellows of the pneumatic spring system often no longer rolls off correctly on the outer wall of the roll-off piston. The consequence thereof are damage caused to the bellows of the pneumatic spring system and also to other components, which may then lead to total failure of a pneumatic spring system. Particularly critical is in this conjunction the condition (b) in which the vehicle is lifted by the crane.
Now, the problem of the invention against the background of said problems consists in providing a pneumatic spring system of the type specified above that is self-closing, so that the vehicle can be lifted by the crane when the pneumatic spring system is in the condition (b) without causing damage to the pneumatic spring system, but the latter will be fully operational again when it is in the condition (a).
Said problem is solved in that
the pneumatic spring system is equipped with a pressure-sensitive connection system that is located within the internal chamber of the pneumatic spring and reacts to pressure in a way such that the pneumatic spring cover and the pneumatic spring piston are connected with each other when the system is in the evacuated condition, and that said connection is released again by the internal pressure when the system is in the operating condition, i.e. when the internal chamber of the pneumatic spring is filled with air.